Radio course indicator



Dec. 24, 1935. R HERMANNSPANN 2,025,104

RADIO COURSE INDICATOR Filed July 8, 1953 INVENTOR PAUL wuzmm BY m APTORNEY- Patented Dec. 24, 1935 Paul Hermannspann, Berlin, Germany, assignor to Telefunken Gesellschaft fiir Drahtlose Telegraphie m. b. H., Berlin, Germany, a corporation of Germany Application July 8, 1933, Serial No. 679,502 In Germany July 2, 1932 6 Claims. (Cl. 250-11) This invention relates to a means to indicate both flying direction or course by radio reception on long waves as well as landing field strength by means of ultra-short wave reception.

Radio direction-finding means are known in the art wherein deviation from the course towards the leftor right-hand side is rendered perceptible by an optical instrument or a telephone. Equipment of this kind generally contains at least two antenna, for instance, a non-directional antenna and a coil antenna with a mechanical or electric change-over switch whereby the connections of the antenna: are alternately switched or whereby the polarity of the coupling between both antenna is reversed at a suitable rhythm or rate. The output end of such an equipment contains as a general rule a telephone receiver and a needle instrument-with center or midpoint adjustment or central zero. 7

Methods are known in the prior art for the purpose of insuring blind landing by means of reception of radio frequency signals. According to this method a transmitter with such a radiation is mounted at the landingpoint that the curves of constant field intensity are suitable landing curves. The receiver instrument required therefor generally comp-risesan antenna, an audion, audio frequency amplifier, telephone and a needle instrument.

According to the invention the said two receiving equipments are so combined that some of the receiving means may be used commonly or jointly. The details of the invention itself and its mode of operation will be best understood from the following description when considered in view of the accompanying drawing in which V Figure 1 shows diagrammatically a circuit embodying a preferred arrangement of receiving apparatus; and

Fig. 2 illustrates diagrammatically a modified arrangement.

Referring first to Fig. 1 an exemplified embodiment of the basic idea of the invention is shown in schematic form. The equipment on the radioguided airplane comprises in this instance an open antenna A and a coil or loop aerial R. The mutual coupling of the two aerials, in a way well known in the art, is rhythmically changed by suitable mechanical or electrical reversing or throw-over means Kl. The radio-guided airplane outfit itself consists of a radio frequency part HF, a detector G and an audio frequency part NF. At the output end of the outfit, by way of a transformer TI, are connected, on the one hand, the telephone receiver Te1,and on the other same time ultra-short waves intended for guid-' ance in effecting a landing may be picked up, the lead from the antenna A to the radio frequency part HF of the radio-guided airplane receiver contains a small choke-coil L which serves to' block the ultra-short waves. In coupling relation with antenna A by way of a small condenser C (of a value of, say, a few centimeters) is the audion, U for ultra-short waves the output end of which is associated with the audio frequency part of the receiver outfit of theairplane. In series with the output transformer Tl of the airplane radio outfit is asecond output transformer T2 with which is united the instrument I2 and'a telephone receiver T62 required for the landing.

The demodulation energies from the detector U for ultra-short waves may be impressed upon the audio frequency amplifier NF, as shown in Fig. 1; On the other hand, these short wave energies may be combined with the long waves by means of apparatus as shown in Fig. 2. In the latter case but one tube G is needed. In this scheme the oscillation circuit SI tuned to the ultra-short wave, and the oscillation circuit S2 tuned to the longer wave are in series with the grid of audion tube G. V

In order to insure sharp separation of the two modulations at the output end of the receiver it is recommended to choose the modulation frequencies of the beacon transmitter and. the transmitter serving as'a guide in efiecting the blind landing as dissimilar as feasible, say, for the former from300-1000 cycles per second and for the latter for example 100 cycles per second, and to design the means with selective action at the output end of the receiver accordingly.

I claim:

1. An aerial navigation system adapted to indicate an airplane course by long wave reception and landing field intensity by ultra-short wave reception, comprising a loop aerial for the long wave reception and an open antenna common to the reception of both long waves and ultra-short waves, switching means for rhythmically and reversibly coupling the loop aerial with the open antenna, a radio frequency amplifier stageconnected on the input side thereof to said switching means, a long wave detector connected to the output side of said amplifier, an ultra-short wave detector coupled to said open antenna, an audiofrequency amplifier having an input circuit adapted to receive demodulation energies from both said detectors, an output circuit for said audio-frequency amplifier including independent 2. An arrangement to indicate an airplane course by long wave reception and landing field intensity by ultra short wave reception, comprising a loop aerial for said course indicator, a common open antenna, switching means for coupling the common open antenna with the loopaerial,

a radio frequency amplifierstage connected to' said switching means, a common audiofrequency amplifier connected to the output of said radio frequency amplifier stage, a choke coil for blocking the ultra short waves connecting said open antenna to said switching means, a variable condenser connecting said open antenna to an audion, the output of said audion being connected to said common audio frequency amplifier stage, the output of said common audio frequency amplifier stage connected to a separate transformer for both the long and short waves, each separate tran former arranged to respond to a different modulated frequency, said transformer connected to a separate indicating device for both the long and short waves.

3. An arrangement to indicate an airplane course by a long wave reception and landing field intensityby ultra short wave reception, comprising a loop aerial for said course indicator, a common open antenna, switching means for coupling the common open antenna with the loop aerial, a radio frequency amplifier stage connected to said switching means, a common audio frequency amplifier connected to the output of said radio frequency amplifier stage, a choke coil for blocking the ultra short waves connecting said open antenna to said switching means, a variable condenser connecting said open antenna to an audion, a first oscillation circuit tuned to the ultra short waves and a second oscillation circuit connected to the long waves, said first and second oscillation circuits connected in series with the input of said audion, the output of saidcommon audio frequency amplifier stage connected to a separate transformer for both the long and short waves, each separate transformer arranged to respond toa'difierent modulated frequency, said transformer connected to a separate indicating device for both the long and short waves.

4. In an aerial navigation system an open antenna and a directional loop antenna, means in circuit with said antenna for amplifying and detecting, in one case, short-wave radio frequency signals indicative of field intensity, and, in another case, long wave radio frequency signals indicative of direction, switching means for reversibly connecting said loop antenna to said open antenna, an audio-frequency amplifier so connected to said detecting means as to amplify the demodulated energies of both' short wave and long wave signals, an output circuit for said audiofrequency amplifier including the primary windings of two transformers, said transformers having respectively different demodulation frequency response characteristics, and a plurality of independent responsive devices, one connected to a secondary winding of one of said transformers, and another to a secondary winding of a different one of said transformers,- V

5. A system in accordance with claim 4 and further characterized in that said amplifying and detecting means for. the radio frequency signals have separate channels for the short waves and the long waves respectively.

6. A system in accordance with claim 4 and having switching means in circuit between one of said transformers that possesses its own demodulation frequency response characteristic and one of said responsive devices.

PAUL HERMANNSPANN. 

